Nanocomposite hydrogel coatings: Formation of metal nanostructures by electrodeposition through thermoresponsive hydrogel layer

Electrode surface was modified with a layer of a nanocomposite. The nanocomposite consisted of electrodeposited nanosized silver structures and thermosensitive hydrogel. The modification procedure consisted of two steps. In the first one, the thermosensitive hydrogel, based on poly(N-isopropylacrylamide) (pNIPA), was electrodeposited. At appropriate temperatures (lower or higher than circa 32 °C) this hydrogel existed either in the swollen- or the shrunken state. Even in the shrunken state, the hydrogel deposited on the electrode surface still contained pinholes and microchannels. Due to this fact, small electroactive redox probes could diffuse to the electrode surface. In the second preparation step the silver nanoobjects were electrodeposited. It was done through the shrunken pNIPA layer. The hydrogel layer acted as a template and finally became one of the components of the composite. We found that the composite adhered satisfactorily to the GC and Pt electrode surfaces. The properties of the composite layers were examined with cyclic voltammetry and scanning electron microscopy. Finally, it was demonstrated that the GC electrodes modified in the proposed manner exhibited electrocatalytic activity. As an example the electroreduction of H2O2 was selected. It appeared that hydrogen peroxide could be successfully determined. The detection limit was found to be 48 μM. The presented approach should enable electrodeposition of other potentially useful metals nanostructures.